Older I get, Better I was
Join Date: Nov 2003
Location: Greenfield Lake, Wilmington NC
Bikes: '14 BD Lurch Fatbike, '10 custom road,'06 custom expedition, '94 Yokota Tandem, '88 custom MTB
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IMO size has a lot to do with how you intend to use the bike. almost all sizing regimes I have seen are based on what a racer needs not a recreational or touring cyclist. Few of us ride like Connie Carpenter or Greg Lemond, On the flip side when was the last time you heard of either of them taking a 1500 mile tour carrying 40 lbs of kit? Racers generally want a flat back and to be stretched out for aerodynamics. They often have the bars several inches lower than the saddle. A tourist ( and most recreational cyclists)on the other hand generally wants higher bars, and the back more upright closer to a 45 degree angle. They often need the bars close to if not above saddle height.
But few shops size you according to what you plan to ride or even what is comfortable. They all size you on a frame that is 2-3cm small, Then you have to buy a high rise stem or a stem extension to get the bars up to a comfortable height. The old rule of thumb( french sizing ?) when I worked in bikeshops and before the compact frame sizing craze was inseam minus 9" for a 700c level top tube frame. that would leave you about 5-6" of seatpost showing. Standover height would almost have your crotch resting on the top tube. Rivendell has a similar sizing scheme and gives a better explanation of it. could it be the reason Rivendell owners like thier bikes so much is that they fit ?!
So using the old timey method: Floor to crotch I am a tad over 34 inches, if I subtract 9" I have 25" (~63 cm) A 63 allows me within the range of a normal road stem to raise or lower the bars above or below my saddle height . Yes 63cm is what I ride (almost 28 years) One caveat though is if you are sizing a cyclo cross bike for road use. The BB is usually a good 1/2- 3/4" or more higher than most road bikes so you need to go at least a centimeter or more smaller. Obviously if you going to cyclocross you would go down 2-3 more centimeters in size.
Using the old formula Someone like Doug who is my height but two inches shorter in the leg would ride a 58 cm but look for a top tube as long as he can find (61cm or longer )
Last edited by velonomad; 01-24-05 at 11:11 PM.